question_answer

Let \[f:(-1,1)\to R\] be a function defined by\[f(x)=max\left\{ -|x|,-\sqrt{1-{{x}^{2}}} \right\}.\] If K be the set of all points at which / is not differentiable, then K has exactly:

A) five elements

B) one element

C) three elements   

D) two elements

Correct Answer: C

Solution :

A, B, C are sharp edges